Russula dissimulans (actual genome source) by Brian P. Looney

Russula dissimulans Shaffer

This genome was sequenced as part of the JGI CSP 1KFG - Deep Sequencing of Ecologically-relevant Dikarya and more specifically as a part of the Russulaceae Sequencing Project, which seeks to densely sample members of a diverse lineage of ectomycorrhizal (ECM) fungi to examine functional diversity of ECM fungi with a shared evolutionary history. Researchers who wish to publish analyses using data from unpublished CSP genomes are respectfully required to contact the PI and JGI to avoid potential conflicts on data use and coordinate other publications with the RSP master paper(s). This genome was derived from culture.

Russula dissimulans is a North American species most closely related to Russula nigricans in a group of 'blackening' Russula species with white to brownish-grey cap colors, whose flesh stains either from red to black or just straight to black. This group is part of the Nigricans clade, which forms an isolated clade along with the Archaea and Farinipes clades (Looney et al. 2016). One of the first biochemical investigations of melanin synthesis was performed on Russula nigricans (Bourquelot and Bertrand 1895), with the cause of the color change later identified as the enzyme tyrosinase acting as the oxidizing agent forming dopachrome (red) and melanin (black) (Seo et al. 2003). Tyrosinases play an important role in human health by synthesizing melanin in skin, thereby providing protection against photocarcinogenesis. Development of tyrosinase inhibitors are also important in the food and cosmetic industries, as tyrosinase leads to undesirable biochemical changes and spoilage. Melanized fungi have even been found living in Chernobyl's reactor, showing radiotropism and potentially using melanin as an energy harvesting pigment similar to chlorophylls (Dadachova and Casadevall 2008). Novel antioxidants and antitumor compounds have been isolated from R. nigricans (Tan et al. 2004). Also, the only known toxic species of Russula, R. subnigricans, belongs in this group, which causes Rhabdomyolysis and has led to the death of at least 7 people (Matsuura et al. 2009). This species is a representative of a large group of Russula species abundant throughout the world and will be important for understanding functional diversity of this lineage.

References

Bourquelot, E. and Bertrand, A., 1895. A re-examination of the Raper's scheme: Cyclodopa as a biological precursor of eumelanin. C. R. Soc. Biol, 47, pp.582-584.

Dadachova, E. and Casadevall, A., 2008. Ionizing radiation: how fungi cope, adapt, and exploit with the help of melanin. Current opinion in microbiology, 11(6), pp.525-531.

Looney, B.P., Ryberg, M., Hampe, F., Sánchez-García, M. and Matheny, P.B., 2015. Into and out of the tropics: global diversification patterns in a hyper-diverse clade of ectomycorrhizal fungi. Molecular ecology, 25(2), pp.630-647.

Matsuura, M., Saikawa, Y., Inui, K., Nakae, K., Igarashi, M., Hashimoto, K. and Nakata, M., 2009. Identification of the toxic trigger in mushroom poisoning. Nature Chemical Biology, 5(7).

Tan, J.W., Xu, J.B., Dong, Z.J., Luo, D.Q. and Liu, J.K., 2004. Nigricanin, the first ellagic acid derived metabolite from the basidiomycete Russula nigricans. Helvetica chimica acta, 87(4), pp.1025-1028.